PagerSnapHelper

Artifact: androidx.recyclerview:recyclerview

Added in 1.0.0

Kotlin |Java

class PagerSnapHelper : SnapHelper

kotlin.Any
↳	androidx.recyclerview.widget.RecyclerView.OnFlingListener
	↳	androidx.recyclerview.widget.SnapHelper
		↳	androidx.recyclerview.widget.PagerSnapHelper

Implementation of the SnapHelper supporting pager style snapping in either vertical or horizontal orientation.

PagerSnapHelper can help achieve a similar behavior to androidx.viewpager.widget.ViewPager. Set both RecyclerView and the items of the RecyclerView.Adapter to have MATCH_PARENT height and width and then attach PagerSnapHelper to the RecyclerView using attachToRecyclerView.

Summary

Public constructors
`PagerSnapHelper()`

Public functions
`IntArray<Int>?`	`calculateDistanceToFinalSnap( layoutManager: RecyclerView.LayoutManager, targetView: View )` Override this method to snap to a particular point within the target view or the container view on any axis.
`View?`	`findSnapView(layoutManager: RecyclerView.LayoutManager!)` Override this method to provide a particular target view for snapping.
`Int`	`findTargetSnapPosition( layoutManager: RecyclerView.LayoutManager!, velocityX: Int, velocityY: Int )` Override to provide a particular adapter target position for snapping.

Protected functions
`RecyclerView.SmoothScroller?`	`createScroller(layoutManager: RecyclerView.LayoutManager)` Creates a scroller to be used in the snapping implementation.

Inherited functions

From androidx.recyclerview.widget.SnapHelper

`Unit`	`attachToRecyclerView(recyclerView: RecyclerView?)` Attaches the `SnapHelper` to the provided RecyclerView, by calling `setOnFlingListener`.
`IntArray<Int>!`	`calculateScrollDistance(velocityX: Int, velocityY: Int)` Calculated the estimated scroll distance in each direction given velocities on both axes.
`LinearSmoothScroller?`	`createSnapScroller(layoutManager: RecyclerView.LayoutManager)` This function is deprecated. use `createScroller` instead.
`Boolean`	`onFling(velocityX: Int, velocityY: Int)` Override this to handle a fling given the velocities in both x and y directions.

Public constructors

PagerSnapHelper

Added in 1.0.0

PagerSnapHelper()

Public functions

Added in 1.4.0

fun calculateDistanceToFinalSnap(
    layoutManager: RecyclerView.LayoutManager,
    targetView: View
): IntArray<Int>?

Override this method to snap to a particular point within the target view or the container view on any axis.

This method is called when the SnapHelper has intercepted a fling and it needs to know the exact distance required to scroll by in order to snap to the target view.

Parameters
`layoutManager: RecyclerView.LayoutManager`	the `RecyclerView.LayoutManager` associated with the attached `RecyclerView`
`targetView: View`	the target view that is chosen as the view to snap

Returns
`IntArray<Int>?`	the output coordinates the put the result into. out[0] is the distance on horizontal axis and out[1] is the distance on vertical axis.

Added in 1.4.0

fun findSnapView(layoutManager: RecyclerView.LayoutManager!): View?

Override this method to provide a particular target view for snapping.

This method is called when the SnapHelper is ready to start snapping and requires a target view to snap to. It will be explicitly called when the scroll state becomes idle after a scroll. It will also be called when the SnapHelper is preparing to snap after a fling and requires a reference view from the current set of child views.

If this method returns null, SnapHelper will not snap to any view.

Parameters
`layoutManager: RecyclerView.LayoutManager!`	the `RecyclerView.LayoutManager` associated with the attached `RecyclerView`

Returns
`View?`	the target view to which to snap on fling or end of scroll

Added in 1.4.0

fun findTargetSnapPosition(
    layoutManager: RecyclerView.LayoutManager!,
    velocityX: Int,
    velocityY: Int
): Int

Override to provide a particular adapter target position for snapping.

Parameters
`layoutManager: RecyclerView.LayoutManager!`	the `RecyclerView.LayoutManager` associated with the attached `RecyclerView`
`velocityX: Int`	fling velocity on the horizontal axis
`velocityY: Int`	fling velocity on the vertical axis

Returns
`Int`	the target adapter position to you want to snap or `NO_POSITION` if no snapping should happen

Protected functions

protected fun createScroller(layoutManager: RecyclerView.LayoutManager): RecyclerView.SmoothScroller?

Creates a scroller to be used in the snapping implementation.

Parameters
`layoutManager: RecyclerView.LayoutManager`	The `RecyclerView.LayoutManager` associated with the attached `RecyclerView`.

Returns
`RecyclerView.SmoothScroller?`	a `RecyclerView.SmoothScroller` which will handle the scrolling.